Getting ready

The Java code for this recipe is located in the org.camelcookbook.routing.changingmep package. The Spring XML files are located under src/main/resources/META-INF/spring and prefixed with changingMep.

How to do it...

Use the inOnly DSL statement to explicitly route a message to that endpoint with that specific MEP:

In the XML DSL, this is written as:

<route>
  <from uri="direct:start"/>
 <inOnly uri="direct:oneWay"/>
  <transform>
    <constant>Done</constant>
  </transform>
</route>

<to uri="direct:oneWay" pattern="InOnly"/>

In the Java DSL, the same thing is expressed as:

from("direct:start")
 .inOnly("direct:oneWay")
  .transform().constant("Done");

to(ExchangePattern.InOnly, "direct:oneWay")

How it works...

When the message reaches the stage in the route that sends to the InOnly endpoint, the MEP associated with the exchange is temporarily changed to InOnly for the call to the specified endpoint and restored on completion of that call.

There is no need to copy the message as this DSL statement is just like a normal to statement sending the message to an endpoint; it just temporarily changes the MEP such that it does not wait for a response from that endpoint.

There's more...

The thread that processes the exchange through the main route is also used to process it through the producer endpoint (direct:oneWay). This makes this pattern very different to a Wire Tap, where we hand over the processing of the message to another thread.

See also